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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 249 (Automatic Transmission - 4L60-E/4L65-E/4L70-E - DTC P0218 To DTC P2771) >> DTC P0787 or P0788 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
  1. Inspect the TRANS fuse for an open.
    • If the fuse is open, test the ignition 1 voltage circuit and the affected control circuit for a short to ground between the Fuse Block-Underhood and the AT inline 20-way connector.
  2. Disconnect the AT inline 20-way connector. Connect the J 44152  jumper harness (20 pins), to the engine side of the connector. See Special Tools . Using the J 35616  GM-approved terminal test kit, connect a test lamp between the ignition 1 voltage circuit and the affected control circuit. Turn ON the ignition with the engine OFF. Using the scan tool output controls command the affected solenoid ON and OFF. The test lamp should blink ON and OFF as commanded.
    • If the test lamp is always OFF, test the circuit for an open.
  3. Connect the J 44152  to the transmission side of the connector. See Special Tools . Using the J 35616  , measure the resistance between the ignition 1 voltage circuit and the affected control circuit. Resistance should be between 20-32 ohms for the 3-2 SS valve.
    • If resistance is greater than the specified range, test the circuits for an open. If the resistance is less than the specified range, test for a faulty solenoid or a shorted together condition.
  4. Measure the resistance between the ignition 1 voltage circuit and the transmission case. The resistance should be greater than 250K ohms.
    • If the resistance is less than 250K ohms, test the ignition 1 voltage circuit for a short to ground.
  5. Measure the resistance between the affected control circuit and ground. The resistance should be greater than 250K ohms.
    • If the resistance is greater than 250K ohms, test the affected control circuit for a short to ground.
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